1. Field of the Invention
The present invention relates to a circuit configuration for an alarm device in circuit breaker units, in particular in power circuit breakers, which have an electronic tripping device and which become effective in the event of a fault in an electrical system to be protected, whereby the electronic tripping device includes a microcontroller which performs a fault evaluation, and for each type of fault makes available an output pin, from which the corresponding fault signal is amplified and transmitted to an electrical relay.
2. Background Information
A circuit breaker unit of the type described above has been described in the form of an NZM 10 Power Circuit Breaker manufactured by the firm of Kloeckner-Moeller, Bonn, Federal Republic of Germany.
The action of the electronic release, or trip device, of this power circuit breaker, which is realized by a corresponding circuit configuration, was described in an advertising publication, W 123-7276, published by Kloeckner-Moeller.
The above-cited publication describes the action of an NZM 10 Power Circuit Breaker which includes a modular system. One of the modules is an alarm, or event, signalling block, which signals the breaker functions "overload tripping", "short circuit tripping" and "load shedding". The alarm signalling block reports Lhe operational status of the breaker locally or remotely. Locally, the event "alarm" or "overload and short circuit tripping" is signalled by an LED display. Its power supply can be between 24 and 240 V AC/DC, and is essentially independent of the main current. Reliable alarm capabilities therefore exist under any operating conditions. For the remote indication of the breaker functions, there are a break contact and a make contact each. The signals are thus available for additional control tasks.
In this system, the contact system of the alarm relay is complex and expensive, since separate contacts are used for the make and break functions. In electronic circuits, a great deal of emphasis is also placed on the lowest possible energy consumption. This low energy consumption is not necessarily optimally achieved in the above-referenced known system, on account of the permanent activation of the relay.
German Patent No. 31 14 551 C2 discloses a circuit breaker unit which includes an electronic tripping device in the form of a microprocessor and an alarm device. The transmission from the circuit breaker to the separate alarm device is pulse coded. For the remote indication of an alarm and tripping, there are two relays. This known system also appears to be unable to eliminate the above-mentioned disadvantages.
Another brochure, published by Kloeckner-Moeller in March 1994, namely W 123-7335, also provides some description of the aforementioned NZM 10 Power Circuit Breaker, and also forms part of the Appendix attached hereto.
Both of the aforementioned brochures which have been included herewith as an Appendix, namely Kloeckner-Moeller brochures W 123-7276 and W 123-7335, are hereby incorporated by reference into the instant specification as if set forth in their entirety herein.